Conventional magnetic random access memory (MRAM) may comprise a stack of several layers. Some of the layers (known as free layers) may comprise ferromagnetic materials, the magnetization of which may be flipped under the effect of an applied magnetic field (free layer), while others (known as fixed layers) have fixed magnetizations.
Normally, the stack sits at the intersection of two cross wires, standing in-between them. These wires provide the magnetic field capable of flipping the magnetization in the free layer by simultaneously passing electric current through them. MRAM cells have two stable magnetization configurations that can be selected by flipping the magnetization from one configuration to the other. One configuration represents a memory state “1” and the other the state “0”.
The stack constitutes a magnetic tunnel junction (MTJ), which has different electric resistance depending on the orientation of the magnetization in the free layer relative to the magnetization in the fixed layer. Normally, MRPM uses the parallel and anti-parallel magnetization configurations to provide two very different values of resistance (low and high, respectively) to represent logical values “1” or “0”. The reading circuitry connected to each cell senses the resistance of the cell by passing current through it.